亚热带季雨林植物罗伞气体交换对光质的反应

亚热带季雨林林下阴生植物罗伞(Ardisia quinquegona)叶片的气体交换速率(PN.μmol.m~(-2),s~(-1))随光强(PFD,μmol,m~(-2),s~(-1))增高而增大。在光强低于80μmol,m~(-2),s~(-1),PN=29.21PFD×10~(-3)+0.36。在光强150μmol,m~(-2),s~(-1)对出现气体交换的光饱和现象。在低光强下,气孔传导率(G,m mol,m~(-2),s~(-1)与光强(m mol,m~(-2),s~(-1)的关系为G=265.6 PFD+4.6。在低光强下。开阔地的阳生灌木桃金娘(Rhodmyrtus tomentosa)的气体交换速率和气孔传导率与光强关系曲线的直线部分斜率皆较罗伞的低,在红光上,罗伞叶片气体交换速率(μmol,m~(-2),s~(-1)与光强(μmol,m~(-2),s~(-1)的关系为PN=32.4 PFD×10~(-3)-0.04。气孔传导率(m mol,m~(-2),s~(-1)与光强(m mol,m~(-2),s~(-1)的关系为G=339.08 PFD+7.37。同时气体交换速率的饱和红光光强亦较白光的高。在蓝光光强低时,气体交换速率(μmol,m~(-2),s~(-1))与光强(μmol,m~(-2),s~(-1))的关系为PN=13.54 PFD×10~(-3)—0.17,而气孔传导率(m mol,m~(-2),s~(-1))与光强(mμmol,m~(-2),s~(-1))的关系为G=80.5 PFD+4.35。在低的蓝光下,体交换速率和气孔传导率与光强关系曲线的直线部分斜率显著较在白光和红光下的低。罗伞叶片气体交换对红光的反应敏感。

THE RESPONSE OF GAS EXCHANGE TO LIGHT QUALITY IN LEAVES OF ARDISIA QUINQUEGONA

The rate of gas exchange (PN, μ mol m-2.s-1) in leaves of Ardisia quinquegona increased with enhancing photon flux density (μ mol. m-2.s-1). The relationship between two parameters was PN=29.21 PFD× 10-8 + 0.36. Leaf conductance (G, m mol.m-2.s-1) increased as photon flux density (PFD, m mol.m-2.s-1) enhanced and the relationship was G=265.6 PFD+4.6. The saturated photosynthesis occurred at 150 μ mol m-2.s-1, As compared with that of Rhodomyrtus tomentosa, a subtropical monsoonal forest shrub, higher initial slopes of gas exchange-light curve and leaf conductance-light curve were observed in Ardisia leaves. The slopes of these relationships were more significant in Ardisia as lighting with red light (>600 nm). The relationship between gas exchange (μ mol. m-2. s-1) and incident density (μ mol.m-2.s-1) of red light was PN= 32.42 PFD×10-8 -0.04 and corresponed relationship between leaf conductance (m mol. m-2.s-1) and incident density (m mol. m-2. s-1) was G-=339.1 PFD+ 7.37. The rate of gas exchange and leaf conductance reduced with lighting blue light (450 nm). And the equations of these regression lines were PN=13.5 PFD×10-3-0.17 and G=80.5 PFD+ 4.35. The results showed that Ardisia leaves might use red light energe efficiently under canopy but it was not sensitive to blue light.